Variable electric control



April 19, 1955 G. J. MUCHER VARIABLE ELECTRIC CONTROL 2 Sheets-Sheet 1Filed Nov. 9, 1951 :DueH L R Q;

April 19, 1

Filed Nov. 9,

955 G. J. MUCHER VARIABLE ELECTRIC CONTROL 1951 2 Sheets-Sheet 2 )Wu M4K w United States Patent VARIABLE ELECTRIC CONTROL George J. Mucher,Rochester, N. H., assignor to Clarostat glfglz Co., Inc., Dover, N. H.,a corporation of New Application November 9, 1951, Serial No. 255,708 6Claims. (Cl. 201-55) This invention relates to a variable control suchas is used in connection with rheostats and potentiometers and aims toprovide a structurally and functionally improved unit of this nature aswell as a method of making the same.

It is an object of the invention to provide a device of this type whichwill have a long effective life and be capable of ready assembly bymeans of relatively unskilled labor so that units embodying the presentteachings may be produced at nominal costs.

A further object of this invention is to provide a device of this typewhich may be of miniature size and yet observe maximum distances betweenthe elements in order to maintain the proper electrical relations.

A further object is that of teaching a method of manufacturing thecontrol which method will include the production of relatively few andrugged parts capable of being readily assembled.

With these and other objects in mind reference is had to the attachedsheets of drawings illustrating practical embodiments of the inventionand in which:

Fig. 1 is a face view showing the formation of a strip throughoutsuccessive steps to provide one of the essential assemblies of thecontrol;

Fig. 2 shows a unit of this assembly after separation from the strip;

Fig. 3 is an edge view of that assembly after it has been subjected to afurther production step;

Fig. 4 is a top plan view of the unit as shown in Fig. 3;

Fig. 5 is a sectional side view of a control constructed in accordancewith the present teachings;

Figs. 6 and 7 are transverse sectional views taken along the lines 6-6and 7-7 respectively and in the direction of the arrows as indicated inFig. 5;

Fig. 8 is a side elevation of the unit as shown in Fi 5;

T ig. 9 is a sectional side view of an assembly embodying multiplecontrols; and

Fig. 10 is a transverse sectional view in enlarged scale taken along thethe line 1010 and in the direction of the arrows as indicated in Fig. 9.

A preferred embodiment of the present control w ll involve a stator androtor assembly. The former Wlll include a resistance traversed by acontact forming a part of the rotor. Also a contact ring will form apart of the stationary units of the stator assembly. This ring willlikewise be traversed by a contact member. Figs. 1 to 4 inclusive havebeen primarily dedicated to 111118- trating the procedure and finishedstructure of the assembly of which the contact members form a part.

Thus, referring to Fig. l, the numeral 10 indicates a strip of metalwhich is formed with what m ght be termed a keyhole opening 11 andannular openings 12 and 13 of diminishing diameters. Conveniently theseopenings are produced at one station. At a succeeding station thematerial is removed from points spaced from openings 11 and 12 tofurnish ring-shaped bodies 14 and 15 having their centers defined by theopenings 11 and 12. Conveniently in line with opening 13 a bar-shapedportion 16 is provided. Rings 14 and 15 are coupled by a connectingportion 17 and a similar portion may intervene ring 15 and bar 16 aswell as the latter and the next adjacent ring.

At the next station ring portion 14 has arms 18 formed to extendsubstantially parallel to the edges defining its opening. These arms aredefined by arcuate shts 19 2,706,760 Patented Apr. 19, 1955 which, as inFig. 1, have their lower ends spaced from each other and their upperends continued through to the offset keyhole portion of opening 11. Atthe next station those portions of ring 14 which are exteriorly of thearms 18 are formed with displaced or tangential parts 20 adjacent thelower ends of the slits 19. These offset portions 20 will serve to urgeand maintain the outer ring body 14 into a plane different from thatinto which arms 18 extend.

The upper end of ring 14 as viewed in Fig. 1 is now provided with abumped out portion 21. A similar portion 22 is formed adjacent the lowerend of ring 15. These portions provide projections which, as willhereinafter be brought out, may function as contact elements. Preferablyafter the formation of these projections, ring 15 has its opening 12enlarged so as to decrease the width of the ring as indicated at 23. Theinner diameter of this ring 23 may be conveniently equal to the externaldiameter of arms 18 and the internal diameter or" the ring part 14beyond such arms.

After severance along the line indicated by dot and dash marks in Fig. la unit as shown in Fig. 2 results. That unit may now be folded uponitself so that connecting part 17 forms a hinge portion extendingsubstantially perpendicular to the surfaces of rings 14 and 23 as wellas arms 18. As shown in Fig. 3 the parts in their positions afterfolding are preferably disposed in a manner such that the bodies ofrings 14 and 23 extend outwardly at an angle with respect to each otherwhile the bodies of arms 18 may extend substantially parallel to thebody of ring 23. Strip 10 comprising a somewhat resilient metal itfollows that all or" the parts may be flexed for example from theposition shown in full lines in 1 Fig. 4 to that indicated in dot anddash lines in that igure.

Now referring to Figs. 5, 6, and 7 it will be seen that a stator ofdi-electric material has been indicated at 24. This stator carries aresistance strip 25 which is secured in position in any desirablemanner. The ends of the strip are connected to terminals 26 convenientlysecured to an extension 27 of the stator body. A cover 28 is applied tothat body and thus forms a part of the stator assembly. The inner faceof the cover supports a contact ring 29 from which a terminal 30 extendsbeyond the surface of the cover. The stator body 24 is provided withprotrusions which coperate with recesses on cover 28 to prevent relativerotation of these parts. To retain the parts of the stator in assembledposition, a strip 31 of metal or other material may bear against theouter face of body 24 and cover 28. Legs 32 extend from the body of thisstrip along the outer side faces of the assembly and terminate in footportions 33 which may be bent inwardly to extend into the recessed outerface of the cover and thus prevent separation of the parts.

A bushing 34 is secured against movement with respect to body 24 andextends outwardly from the rear face of the same to mount upon itsthreaded exterior a nut 35 which may retain the assembly in associationwith a mounting panel indicated in dot and dash lines. An operatingshaft 36 extends rotatably within the bore of the bushing and may beformed with a groove 37 in line with the outer end of the latter. Aretaining element such as a C washer is conveniently disposed withinthis groove and thus prevents the shaft being axially displaced in aninward direction with respect to the assembly. It is apparent that whenthe shaft is turned, any rotor grouping attached to its inner end willbe similarly moved with respect to the stator assembly.

Conveniently the bushing may provide adjacent the outer face of stator24 a non-circular portion 40. Against one of the edges of this portionstrip 31 may bear to prevent a relative rotation of that strip withrespect to the assembly. The inner end portion of shaft 36 is preferablyreduced as at 41 and upon thls reduced portion mounts a plate 42conveniently of metal. The latter may be recessed into the rear face ofthe rotor body 39 formed of dielectric material. That face of the statorwhich is adjacent the rotor body 39 may be formed with an outstandingedge portion 43. This will provide a bearing surface and also restrictaxial movement of the rotor. The latter being secured in positionconveniently by a washer 44 bearing against its outer face and beyondwhich the reduced portion 41 of the shaft is headed, it

follows that axial movement of the rotor assembly and its shaft in adirection towards the resistance strip 25 is prevented.

The rotor has upon its outer face an annular ridge 45 which is providedwith outstanding end portions 46 extending in the direction of anenlarged portion 47 of the rotor. As shown especially in Fig. 5, theouter part of the rotor 39 is spaced from and may extend in overlappingrelationship with respect to the contact strip 25. In mounting thecontact member upon the rotor it is, of course, apparent that thisoperation is achieved before the rotor is affixed to the extended shaftportion 41. The connecting portion 17 bridges across the edge of therotor at a point diametrically opposite the extended part 47. The armsor fingers 18 encircle the ridge or rib 45; the diameter of the opening11 being such that these arms will grip the side faces of the rib andthus retain the contact member in position. The ends of arms 18 bearagainst the side edges of the extended portion 47. Due to the offsetportions 20 which are preferably employed, the ring 14 extends at anangle to the outer face of the rotor as shown in Fig. 5. Its projection21 may overlie portion 47. In any event with cover 28 in position thisprojection will serve as a contact and traverse the surface of ring 29.Ring 23 encircles the inner portion of the rotor 39. Its projecting part22 serves as a contact in cooperation with the surface of the resistancestrip 25.

Thus it is apparent that with the parts assembled in the manner shownthe contact portions 21 and 22 of the assembly as shown in Figs. 3 and 4will serve to provide electrical connection between the terminals 26 and30. By rotating the shaft 36 the values within the circuits may bevaried. Due to the manner in which the shaft and rotor are supportedwith respect to the parts of the stator assembly no axial shifting ofthese parts will occur. Also, due to the manner in which the cover 28 issecured to and forms a part of the stator assembly, the several portionsof the latter will not shift with respect to each other. The resiliencyof the material providing the contact assembly as in Figs. 3 and 4 willassure a proper cooperation of these parts with the adjacent ring andresistance surfaces throughout a long effective life.

It is, of course, obvious that any desired number of controls embodyingthe foregoing teachings might be combined. This has been shown in Fig. 9in which a pair of these units have been illustrated. In that view thetwo stators are indicated at 48 and 49 and with which the rotorassemblies 50 and 51 cooperate. The operating shaft is provided with arelatively lengthy extended end portion 52 of non-circularcross-section. A spacer unit 53 may be interposed between the rotors 50and 51 and encircle the shaft portion 52. To this end and as shown inconnection with the cover 28 of the earlier figures the cover of theright hand assembly as viewed in Fig. 9 may be provided with a reducedportion 54 which is simply .knocked out. In this manner an openingadequate to receive shaft 52 and spacer sleeve 53 is provided. Thatshaft, as shown in Fig. 10, may conveniently be noncircular similar tothe extended shaft portion 41 of the earlier figures. The retainer whichmaintains the cover and main stator body in assembled relationship will,in the instance of Fig. 9, simply include longer leg portions 55 suchthat it may engage the outer surfaces of the two outermost units.

Thus, among others, the several objects of the invention as specificallyaforenoted are achieved. It is obvious that bodies 1.4 and 15 may embodyany desired configurations compatible with the unit being incorporatedas part of the rotor assembly. Also, these bodies need not embracering-shaped outlines. Additionally, numerous other changes inconstruction and rearrangement of the parts might be resorted to and thesteps of the method might be varied without departing from the spirit ofthe invention as defined by the claims.

I claim:

I. A variable control assembly including in combination a statorcomprising axially spaced resistance and contact elements, a rotorshaft, a contact carrier secured to said rotor shaft and interveningsaid elements, a pair of connected rotor shaft encircling portions, aprojection extending from said rotor, an arm integral with one of saidportions to engage said projection, said encircling portions and armbeing formed of resilient material, an offset portion adjacent said armto maintain one portion at an angle with respect to the other and partsforming units of said portions to engage and traverse said statorelements.

2. A contact assembly for a variable control comprising a pair ofrotor-encircling portions, a bridging part connecting said portions,contacts associated with each of said portions and an arm extending fromone of said portions and to provide a mounting in engagement with facesof a rotor.

33. A contact assembly for a variable control comprising a pair ofrotor-encircling portions, a bridging part connecting said portions,contacts associated with each of said portions, an arm extending fromone of said portions and to provide a mounting in engagement with facesof a rotor and an offset part disposed adjacent said arm to cause saidportions to extend angularly with respect to each other.

4. A variable control including in combination a rotor body, a pair ofconducting elements disposed one adjacent each of the opposite faces ofsaid body, a portion connecting said elements and extending across anedge of said body, an abutment forming a part of said body, an armformed from a part of one of said elernents and said arm engaging asurface of said abutment to prevent relative turning of said elementswith respect to said body.

5. A variable control including in combination a rotor body, a pair ofconducting elements disposed one adjacent each of the opposite faces ofsaid body, a portion connecting said elements and extending across anedge of said body, an abutment forming a part of said body, an armformed from a part of one of said elements, said arm engaging a surfaceof said abutment to prevent relative turning of said elements withrespect to said body and said arm being sprung beyond the plane of theelement from which it extends to yieldingly engage the adjacent surfaceof said body and urge said element away from the surface of the same.

6. A variable control assembly including in combination a statorcomprising axially spaced resistance and contact elements, a rotorshaft, a contact carrier intervening said elements carried by said rotorshaft, 8. pair of connected rotor shaft encircling portions, an armintegral at one end thereof with one of said portions, said arm beingsecured against rotations relative to said shaft, and parts formingunits of said portions to engage and traverse said stator elements.

References Cited in the file of this patent UNITED STATES PATENTS2,040,277 Siegel May 12, 1936 2,040,278 Siegel May 12, 1936 2,206,662Conradi et al July 2, 1940 2,446,417 Hastings Aug. 3, 1948 2,454,816Levy Nov. 30, 1948 2,458,552 Blattner Jan. 11, 1949

